Field:
The invention relates to a method for assisting a driver in driving a vehicle and a corresponding driver assistance system.
Detailed Description of the Related Art:
In recent years, a great progress has been achieved with respect to autonomous driving or at least assisting a driver in driving by presenting information that the driver himself is usually not capable of recognizing while driving has been made. On the one hand, this increased the comfort for the driver because he can concentrate on things that still need to be done by the driver himself while on the other side such systems assist the driver for example by keeping a speed constant at a value that was previously set by the driver. Systems have been developed which are not capable of maintaining a constant speed only but also take into consideration the environment of the ego vehicle that is equipped with such a system. In order to achieve this object the ego vehicle is equipped with sensing means that can obtain information from the environment of the ego vehicle. By evaluating this information, the ego vehicle is for example capable of recognizing a vehicle driving right in front of the ego vehicle but with a lower speed. As a consequence, it is determined by the ego vehicle's driver assistance system that maintaining the current speed would lead to a collision with the predecessor of the ego vehicle. Thus, the ego vehicle can automatically be slowed down and the speed can be adjusted so that the ego vehicle follows its predecessor at a constant gap. Such cruise control is a simple example of a driver assistance system and shows only the first step on a long way of development part of which only has been gone. While the sensing means was used in the beginning only for fulfilling simple tasks during the process of further developments, it was recognized that additional information can be derived from the environment which is physically sensed by such system. Examples are predictions of future trajectories of other traffic participants as it is described for example in US 2013/0238181 A1. But not only the relative speed and direction of the other traffic participants can be estimated on the basis of signals of radar systems or video cameras that physically sense the environment of the ego vehicle, but also static traffic elements can be detected.
Examples for such static traffic elements are lane markings or the like. Furthermore, by evaluation of the behavior of the other traffic participants, additional information can be obtained that describe a scene the ego vehicle is part of. For example it is possible to analyze the relative positions and velocities of other traffic participants like other vehicles and thus, conclude where neighboring lanes of a multi lane road are. Such approach is described in U.S. Pat. No. 7,379,815 B2. Another approach is described in 10 2012 214 206 A1 where it is disclosed that a lane curvature can be derived from car positions of other traffic participants.
One big disadvantage of all these systems and further systems that may exist relying on the capability of sensing means mounted on an ego vehicle is that the information the system may obtain is limited to anything that can be derived directly from elements, vehicles, persons, that are visible to the sensing means. But in many cases it would of course be interesting and may be highly relevant for an analysis of a traffic situation what is hidden by other objects or what lies outside the sensing range of the sensor means. Such hidden areas are in particular interesting in case that for example an occupancy grid is generated, thus providing the system with information which areas are usable by the ego vehicle. Such occupancy grids are often used in order to plan a path which is suitable for the ego vehicle in order to move on from its current position to an intermediate way point that lies for example on a route that was calculated by a navigation system. With such path planning, the driver is assisted for example by presenting him information guiding him through an area corresponding to a representation of the environment such as for example a two dimensional map. Two dimensional maps itself is of course known for example from navigation systems but such navigation systems cannot be a basis for the path planning for the ego vehicle since the information included in such a navigation map is limited to a very coarse definition of roads and buildings. The actual boundaries such as a pavement next to a road for example is not included as information in the navigation map. But for path planning which is performed on a different level of details in a close surrounding, it is essential that in fact the concrete paths through the near surrounding of the ego vehicle is possible. Thus, for such path planning it would be highly relevant if there are for example obstacles or areas where the vehicle cannot drive on like pavements and the like.